Non-invasive monitor for measuring regional saturation of oxygen

ABSTRACT

A non-invasive monitor for measuring regional saturation of oxygen includes a sensor unit containing a printed circuit board on which a light emitting unit and a light receiving unit are mounted; a main body unit; a sensor holder for holding the sensor unit while the light emitting unit and the light receiving unit are disposed in an aperture portion; a sensor pressing board; a connecting unit for electrically connecting the sensor unit and the main body unit; and a headband. The light emitting unit and the light receiving unit are disposed such that a light emitting surface and a light receiving surface face the forehead-side, and a part or the whole of the forehead-side surface of the sensor unit is on the same surface as the forehead-side surface of the sensor holder or protrudes from the forehead-side surface of the sensor holder toward the forehead-side.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. Nationalization of PCT Application NumberPCT/JP2015/050823, filed on Jan. 14, 2015, which claims priority to JPPatent Application No. 2014-014706, filed on Jan. 29, 2014, theentireties of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a non-invasive monitor for measuringregional saturation of oxygen, which is light and compact, and hasexcellent portability and handleability.

BACKGROUND ART

In recent years, particularly in emergency medicine, it has come to beknown to significantly improve a rehabilitation rate of a cardiac arrestpatient by emergency life-saving measures by a doctor or an emergencymedical technician while a regional saturation of oxygen (rSO₂) of thecardiac arrest patient is monitored using a near-infrared ray (forexample, refer to Patent Literatures 1 and 2). Generally, for example,as illustrated in FIG. 1 of Patent Literature 2, a structure of anapparatus for monitoring a regional saturation of oxygen (rSO₂) using anear-infrared ray is separated into a probe unit attached to theforehead of a patient's head and an apparatus main body unit having acircuit board for analyzing a signal from the probe unit and a displayunit for displaying an analysis result integrated, and the probe unitand the apparatus main body unit are connected with a long signal cable.

CITATION LIST Patent Literature

[Patent Literature 1] JP 5062698 B1

[Patent Literature 2] JP 2013-170881 A

SUMMARY OF INVENTION Technical Problem

Such a structure of an apparatus as illustrated in FIG. 1 of PatentLiterature 2 does not particularly cause a problem in a hospital forreceiving a cardiac arrest patient. However, in an emergency site suchas outside a hospital or in an emergency vehicle, a working space andpersonnel are limited. Therefore, when an operator such as a doctor oran emergency medical technician performs emergency life-saving measuresin an emergency life-saving site, an apparatus with a probe unit and anapparatus main body unit separated has a problem in terms of size, mass,easiness of handling, or the like due to hindrance of space of the siteor narrowness of the space. Therefore, in the emergency life-savingsite, appearance of a non-invasive monitor for measuring regionalsaturation of oxygen in which a probe unit and an apparatus main bodyunit are integrated, which is light and compact, and has excellentportability and excellent handleability to make an operator handle themonitor easily, has been desired.

An object of the present invention is to provide a non-invasive monitorfor measuring regional saturation for oxygen which is light and compact,and has excellent portability and excellent handleability to make anoperator handle the monitor easily.

Solution to Problem

A non-invasive monitor for measuring regional saturation of oxygenaccording to the present invention measures an oxygen saturation of abrain blood stream continuously in a non-invasive manner by mounting themonitor on a person's head, and includes at least a sensor unitcontaining a printed circuit board on which a light emitting unit forirradiating a surface of the forehead of the head with light of 650 to1000 nm and a light receiving unit for receiving light which has beenemitted by the light emitting unit and has propagated inside the headare mounted; a main body unit disposed in front of the forehead whenbeing mounted on the head, containing a computation processing unit forcalculating a mixed oxygen saturation of the brain blood based on adetection signal detected by the sensor unit, a display unit fordisplaying a computation processing result by the computation processingunit, and a power source unit for supplying power to the sensor unit,the computation processing unit, and the display unit; a sensor holderfor holding the sensor unit while the light emitting unit and the lightreceiving unit are disposed in an aperture portion, having a board shapeabutting on the forehead and containing the aperture portion penetratingin a board thickness direction thereof; a sensor pressing board forholding the sensor unit toward the sensor holder, disposed between thesensor unit and the main body unit; a connecting unit for electricallyconnecting the sensor unit and the main body unit; and a headband formounting the main body unit on the head detachably, characterized inthat the light emitting unit and the light receiving unit are disposedsuch that a light emitting surface of the light emitting unit and alight receiving surface of the light receiving unit face theforehead-side, and a part or the whole of the forehead-side surface ofthe sensor unit is on the same surface as a forehead-side surface of thesensor holder or protrudes from the forehead-side surface of the sensorholder toward the forehead-side.

The non-invasive monitor for measuring regional saturation of oxygenaccording to the present invention preferably further includes a cushioninterposed between the main body unit and the sensor pressing board. Bybringing the sensor unit into closer contact with the forehead, entranceof light from the outside into the light receiving unit can besuppressed, and measurement can be performed with higher accuracy.

In the non-invasive monitor for measuring regional saturation of oxygenaccording to the present invention, preferably, the sensor unit includesa right light emitting unit and a left light emitting unit as the lightemitting unit and a right light receiving unit and a left lightreceiving unit as the light receiving unit, the left light receivingunit, the left light emitting unit, the right light emitting unit, andthe right light receiving unit are disposed in this order in a lateraldirection of the forehead, the left light emitting unit and the rightlight emitting unit are disposed in linear symmetry with a virtualstraight line between the left light emitting unit and the right lightemitting unit as a symmetric axis, and the left light receiving unit andthe right light emitting unit are disposed in linear symmetry with thevirtual straight line as a symmetric axis. The oxygen saturation of theright brain and left brain can be measured at the same time.

In the non-invasive monitor for measuring regional saturation of oxygenaccording to the present invention, preferably, the main body unit has acenter mark, and the position of the center mark in a lateral directionof the forehead is on the virtual straight line. An operator can easilyconfirm the positions of the right light emitting unit and the leftlight emitting unit. By mounting the monitor by matching the center markwith the center portion in a lateral direction of the forehead of apatient, the oxygen saturation of the right brain and left brain can bemeasured more securely and more accurately.

In the non-invasive monitor for measuring regional saturation of oxygenaccording to the present invention, preferably, the headband includes aninner headband connected to the main body unit, an outer headbandconnected to the outside of the inner headband, and a connecting portionconnecting the outer headband to the inner headband so as to be able tobe tightened or loosened, the inner headband includes a slide grooveportion, the connecting portion includes a shaft portion engaging withthe slide groove portion, and the headband can lift the outer headbandaround the shaft portion and can adjust the position of the outerheadband by sliding the shaft portion along the slide groove portion andmatching the headband with the size of the head. The monitor can bemounted on a patient more easily. An operator alone can mount themonitor due to the lifting type outer headband.

The non-invasive monitor for measuring regional saturation of oxygenaccording to the present invention preferably further includes atightening tool connected to the sensor pressing board. By bringing thesensor unit into closer contact with the forehead, entrance of lightfrom the outside into the light receiving unit can be suppressed, andmeasurement can be performed with higher accuracy.

In the non-invasive monitor for measuring regional saturation of oxygenaccording to the present invention, the connecting unit is preferably aconnector. By no use of a cable, a problem that work is hindered becausea cable is caught does not occur. The size of the non-invasive monitorfor measuring regional saturation of oxygen can be smaller. Theconnector also serves as a fixing tool for fixing the sensor unit to themain body unit.

In the non-invasive monitor for measuring regional saturation of oxygenaccording to the present invention, preferably, the sensor unit includesa covering portion for covering a part or the whole of the forehead-sidesurface of the sensor unit, and the covering portion includes a siliconeportion made of silicone and transmitting the light at least in aportion covering the light emitting surface-side of the light emittingunit and a portion covering the light receiving surface-side of thelight receiving unit. A contaminant adhering to the light emittingsurface and the light receiving surface can be wiped off more easily. Byreplacing the covering portion, it is possible to keep the lightemitting surface and the light receiving surface clean all the time.

In the non-invasive monitor for measuring regional saturation of oxygenaccording to the present invention, preferably, the covering portionincludes a light transmission hindering portion at least between thesilicone portion covering the light emitting unit and the siliconeportion covering the light receiving unit, and the transmittance of thelight in terms of a thickness of 1 mm in the light transmissionhindering portion is one tenth or less with respect to the transmittanceof the light in terms of a thickness of 1 mm in the silicone portion. Bytransmission of light not propagating inside the head through thesilicone portion, entrance of the light into the light receiving unitcan be suppressed, and measurement can be performed with higheraccuracy.

In the non-invasive monitor for measuring regional saturation of oxygenaccording to the present invention, the sensor unit preferably includesa light receiving unit for a shallow portion and a light receiving unitfor a deep portion as the light receiving unit. Measurement can beperformed with higher accuracy.

Advantageous Effects of Invention

The present invention can provide a non-invasive monitor for measuringregional saturation of oxygen which is light and compact, and hasexcellent portability and excellent handleability to make an operatorhandle the monitor easily.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 exemplifies a non-invasive monitor for measuring regionalsaturation of oxygen according to the present embodiment, and is aperspective view illustrating the monitor partially exploded.

FIG. 2 is a plan view exemplifying the non-invasive monitor formeasuring regional saturation of oxygen according to the presentembodiment.

FIG. 3 is a front view exemplifying the non-invasive monitor formeasuring regional saturation of oxygen according to the presentembodiment.

FIG. 4 is a right side view exemplifying the non-invasive monitor formeasuring regional saturation of oxygen according to the presentembodiment.

FIG. 5 exemplifies the non-invasive monitor for measuring regionalsaturation of oxygen according to the present embodiment, and is aperspective view seen from the upper front face.

FIG. 6 exemplifies the non-invasive monitor for measuring regionalsaturation of oxygen according to the present embodiment, and is aperspective view seen from the upper rear face.

FIG. 7 is a plan view exemplifying a sensor unit.

FIG. 8 is a cross sectional view cut along line A-A in FIG. 7.

FIG. 9 is a cross sectional view illustrating a first example of acovering portion.

FIG. 10 is a cross sectional view illustrating a second example of thecovering portion.

FIG. 11 is a diagram illustrating a state in which an outer headband islifted.

FIG. 12 is a diagram illustrating a state in which the monitor ismounted on a person having a small head.

FIG. 13 is a diagram illustrating a state in which the monitor ismounted on a person having a large head.

FIG. 14 is a diagram illustrating a state in which a tightening tool istightened.

FIG. 15 is a diagram illustrating a state in which the tightening toolis loosened.

FIG. 16 is a schematic diagram illustrating a modification example of amain body unit.

DESCRIPTION OF EMBODIMENTS

Next, the present invention will be described in detail by describingembodiments, but the present invention is not construed as being limitedto description thereof. As long as an effect of the present invention isexhibited, the embodiments may be modified variously.

A non-invasive monitor for measuring regional saturation of oxygen 1according to the present embodiment measures an oxygen saturation of abrain blood stream continuously in a non-invasive manner by mounting themonitor on a person's head, and includes at least, as illustrated inFIG. 1, a sensor unit 10 containing a printed circuit board on whichlight emitting units 11,12 for irradiating a surface of the forehead ofthe head with light of 650 to 1000 nm and light receiving units 13,14for receiving light which has propagated inside the head of the lightemitted by the light emitting units 11,12 are mounted; as illustrated inFIGS. 2 to 5, a main body unit 20 disposed in front of the forehead whenbeing mounted on the head, containing a computation processing unit (notillustrated) for calculating a mixed oxygen saturation of the brainblood based on a detection signal detected by the sensor unit 10, adisplay unit 21 for displaying a computation processing result by thecomputation processing unit, and a power source unit (not illustrated)for supplying power to the sensor unit 10, the computation processingunit, and the display unit 21; as illustrated in FIGS. 1 and 6, a sensorholder 30 for holding the sensor unit 10 while the light emitting units11,12 and the light receiving units 13,14 are disposed in an apertureportion 31, having a board shape abutting on the forehead and containingthe aperture portion 31 penetrating in a board thickness directionthereof; a sensor pressing board 40 for holding the sensor unit 10toward the sensor holder 30, disposed between the sensor unit 10 and themain body unit 20; a connecting unit 50 for electrically connecting thesensor unit 10 and the main body unit 20; and a headband 60 for mountingthe main body unit 20 on the head detachably. The light emitting units11,12 and the light receiving units 13,14 are disposed such that lightemitting surfaces of the light emitting units 11,12 and light receivingsurfaces of the light receiving units 13,14 face the forehead-side and apart or the whole of the forehead-side surface of the sensor unit 10 ison the same surface as a forehead-side surface of the sensor holder 30or protrudes from the forehead-side surface of the sensor holder 30toward the forehead-side.

The non-invasive monitor for measuring regional saturation of oxygen 1according to the present embodiment measures an oxygen saturation (rSO₂)of a brain blood stream continuously in a non-invasive manner bynear-infrared spectroscopy (NIRS).

FIG. 7 is a plan view exemplifying a sensor unit. FIG. 8 is a crosssectional view cut along line A-A in FIG. 7. The sensor unit 10 is aboard-shaped member which can be bent according to the shape of theforehead. The sensor unit 10 includes a printed circuit board 15 asillustrated in FIG. 8.

In the printed circuit board 15 electronic components such as the lightemitting units 11,12 and the light receiving units 13,14 are mounted ona flexible wiring board. For example, the flexible wiring board has astructure obtained by laminating a substrate film layer of a polyesterfilm and a polyimide film, an adhesive layer, and a conductive foillayer such as copper foil sequentially. The present invention is notlimited by the structure of the flexible wiring board. In a mountedsurface of the printed circuit board 15, a portion other than the lightemitting units 11,12 or the light receiving units 13,14 is preferablycovered with a probe cover 16. A material of the probe cover 16 is notparticularly limited, but for example, is an elastomer such as siliconerubber. The probe cover 16 preferably has a protrusion 16 a formed bymaking a region including the light emitting units 11,12 and the lightreceiving units 13,14 relatively protrude compared with the otherregions. As illustrated in FIG. 6, by fitting the protrusion 16 a intothe aperture portion 31 of the sensor holder 30, the sensor unit 10 canbe held by the sensor holder 30 more firmly. The probe cover 16 may bedisposed on a rear surface of the mounted surface of the printed circuitboard 15 in addition to the mounted surface.

For example, each of the light emitting units 11,12 is a light emittingelement such as a light emitting diode (LED). The light emitting units11,12 are disposed such that light emitting surfaces thereof face theforehead-side. The light emitting units 11,12 are preferably surroundedby a frame portion 18. By bringing the frame portion 18 into closecontact with the forehead, the forehead can be irradiated with lightemitted by the light emitting units 11,12 more efficiently. The lightemitted by the light emitting units 11,12 is near-infrared light of 650to 1000 nm. The light emitting units 11,12 can preferably output two ormore kinds of light having different wavelengths sequentially. Forexample, the two or more kinds of light having different wavelengths islight having two wavelengths of 730 nm and 810 nm.

For example, each of the light receiving units 13,14 is a lightreceiving element such as a photodiode. The light receiving units 13,14are disposed such that light receiving surfaces thereof face theforehead-side. The light receiving units 13,14 are preferably surroundedby the frame portion 18. After the light emitted by the light emittingunits 11,12 propagates inside the head, the light receiving units 13,14can receive the light more efficiently by bringing the frame portion 18into close contact with the forehead.

The sensor unit 10 preferably includes light receiving units for ashallow portion 13 a and 14 a and light receiving units for a deepportion 13 b and 14 b as the light receiving units 13,14. By includingthe light receiving units for a shallow portion 13 a and 14 a and thelight receiving units for a deep portion 13 b and 14 b, measurement canbe performed with higher accuracy. A distance d2 between the lightreceiving units for a deep portion 13 b and 14 b and the light emittingunits 11,12 is preferably longer than a distance d1 between the lightreceiving units for a shallow portion 13 a and 14 a and the lightemitting units 11,12. The distance d1 between the light receiving unitsfor a shallow portion 13 a and 14 a and the light emitting units 11,12is a distance of light from emission by the light emitting units 11,12until arrival at a surface of the forehead through a shallow layer ofthe brain, and is for example, preferably 0.1 mm or more and 35 mm orless, and more preferably 0.5 mm or more and 30 mm or less. The distanced2 between the light receiving units for a deep portion 13 b and 14 band the light emitting units 11,12 is a distance of light from emissionby the light emitting units 11,12 until arrival at a surface of theforehead through a deep layer of the brain, and is for example,preferably more than 35 mm and 60 nm or less, and more preferably 40 mmor more and 50 mm or less. The distances d1 and d2 are examples, and thepresent invention is not limited thereto. By disposing the two lightreceiving units for a deep portion 13 b (14 b) in parallel, thecomputation processing unit (not illustrated) can calculate a regionalsaturation of oxygen without creating a calibration curve.

As illustrated in FIG. 7, preferably, the sensor unit 10 includes aright light emitting unit 11 and a left light emitting unit 12 as thelight emitting units 11,12 and a right light receiving unit 13 and aleft light receiving unit 14 as the light receiving units 13,14, theleft light receiving unit 14, the left light emitting unit 12, the rightlight emitting unit 11, and the right light receiving unit 13 aredisposed in this order in a lateral direction of the forehead, the leftlight emitting unit 12 and the right light emitting unit 11 are disposedin linear symmetry with a virtual straight line L between the left lightemitting unit 12 and the right light emitting unit 11 as a symmetricaxis, and the left light receiving unit 14 and the right light receivingunit 13 are disposed in linear symmetry with the virtual straight line Las a symmetric axis. The oxygen saturation of the right brain and leftbrain can be measured at the same time.

FIG. 9 is a cross sectional view illustrating a first example of acovering portion. FIG. 9 illustrates a cross section of a positioncorresponding to line A-A in FIG. 7. Preferably, the sensor unit 10includes a covering portion 17 for covering a part or the whole of theforehead-side surface of the sensor unit 10, and the covering portion 17includes silicone portions 17 a and 17 b made of silicone andtransmitting light at least in a portion covering the light emittingsurface-sides of the light emitting units 11,12 and a portion coveringthe light receiving surface-sides of the light receiving units 13,14. Bydisposing the silicone portions 17 a and 17 b, it is possible to preventa contaminant from adhering to the light emitting surface and the lightreceiving surface and to wipe off the contaminant adhering to thesilicone portions 17 a and 17 b easily. By replacing the coveringportion 17, it is possible to keep the light emitting surface and thelight receiving surface clean all the time. FIG. 9 illustrates a form inwhich the covering portion 17 covers a surface of the protrusion 16 a ofthe forehead-side surface of the sensor unit 10, but the presentinvention is not limited thereto, and for example, may be a form inwhich the covering portion 17 covers only the light emitting surfaces ofthe light emitting units 11,12 and the light receiving surfaces of thelight receiving units 13,14 (not illustrated), or a form in which thecovering portion 17 covers the whole of the forehead-side surface of thesensor unit 10. FIG. 9 illustrates a form in which the silicone portions17 a and 17 b are disposed only on the light emitting units 11,12 andthe light receiving units 13,14, but the silicone portions 17 a and 17 bmay cover the whole of the forehead-side surface of the sensor unit 10.The silicone is, for example, silicone rubber. The transmittance oflight emitted by the light emitting units 11,12 in terms of a thicknessof 1 mm in the silicone portions 17 a and 17 b is preferably 60% ormore, and more preferably 80% or more.

As illustrated in FIG. 9, preferably, the covering portion 17 includes alight transmission hindering portion 17 c at least between the siliconeportion 17 a covering the light emitting units 11,12 and the siliconeportion 17 b covering the light receiving units 13,14, the transmittanceof light emitted by the light emitting units 11,12 in terms of athickness of 1 mm in the light transmission hindering portion 17 c isone tenth or less with respect to the transmittance of the light interms of a thickness of 1 mm in the silicone portions 17 a and 17 b. Thetransmittance of light is more preferably one twentieth or less. Bydisposition of the light transmission hindering portion 17 c, entranceof light into the light receiving units 13,14 can be suppressed bytransmission of light not propagating inside the head through thesilicone portions 17 a and 17 b, and measurement can be performed withhigher accuracy. The light transmission hindering portion 17 c may bedisposed between the silicone portions 17 b covering the light receivingunits 13,14 in addition to between the silicone portion 17 a coveringthe light emitting units 11,12 and the silicone portion 17 b coveringthe light receiving units 13,14. A preferable form of the coveringportion 17 is, for example, a form in which the light transmissionhindering portion 17 c is a sheet provided with apertures in a laddershape at positions corresponding to the light emitting units 11,12 andthe light receiving units 13,14, and the silicone portions 17 a and 17 bare embedded into the apertures of the light transmission hinderingportion 17 c to form a shape of one sheet as a whole. In the form inwhich the silicone portions 17 a and 17 b and the light transmissionhindering portion 17 c form a shape of one sheet, the light transmissionhindering portion 17 c is preferably made of silicone rubber containinga black pigment such as carbon black.

FIG. 10 is a cross sectional view illustrating a second example of acovering portion. FIG. 10 illustrates a cross section of a positioncorresponding to line A-A in FIG. 7. As illustrated in FIG. 10, it ispreferable that a covering portion includes a light transmissionhindering portion 91 disposed on the forehead-side surface of the sensorunit 10 and provided with apertures 91 a in a ladder shape at positionscorresponding to the light emitting units 11, 12 and the light receivingunits 13, 14; and a light-transmitting silicone portion 92 disposed on alight transmission hindering portion 91 and block the apertures 91 a.The light transmission hindering portion 91 is interposed between theadjacent apertures 91 a, therefore entrance of light not propagatinginside the head through the silicone portion 92 into the light receivingunits 13, 14 can be suppressed, and measurement can be performed withhigher accuracy. When a contaminant adheres, only the silicone portion92 can be replaced. The silicone portion 92 is preferably fixed to asurface of the light transmission hindering portion 91. A fixing methodis not particularly limited, but is a heat fusion method or a methodusing an adhesive or a pressure-sensitive adhesive. As silicone used forthe silicone portion 92, the same kind as the silicone portions 17 a and17 b described in the first example of the covering portion can be used.The transmittance of light emitted by the light emitting units 11, 12 interms of a thickness of 1 mm in a silicone portion 92 is preferably 60%or more, and more preferably 80% or more. The light transmissionhindering portion 91 is, for example, made of a resin containing a blackpigment such as carbon black. The kind of the resin is not particularlylimited, but is, for example, polyethylene terephthalate, nylon, orsilicone. The transmittance of light emitted by the light emitting units11, 12 in terms of a thickness of 1 mm in the light transmissionhindering portion 91 is preferably one tenth or less with respect to thetransmittance of the light in terms of a thickness of 1 mm in thesilicone portion 92. As illustrated in FIG. 10, a more preferable formis a form in which the silicone portion 92 is formed of a plurality ofsheets slightly larger than each aperture 91 a of the light transmissionhindering portion 91 and each sheet blocks each aperture 91 a to form agap between the adjacent silicone portions 92.

As illustrated in FIGS. 8 and 9, the connecting unit 50 is preferablydisposed on a rear surface of the mounted surface of the sensor unit 10.The connecting unit 50 is, for example, a connector such as a plug-inconnector or a ribbon connector or a cable such as a plug-in cable or aribbon cable. Among these, the connecting unit 50 is preferably aconnector. By no use of a cable, a problem that work is hindered becausea cable is caught does not occur. The size of the non-invasive monitorfor measuring regional saturation of oxygen 1 can be smaller. Theconnector also serves as a fixing tool for fixing the sensor unit 10 tothe main body unit 20. For example, as illustrated in FIG. 2, theconnecting unit 50 is connected to a recess type connector (notillustrated) disposed in the main body unit 20 through a through hole 41disposed in the sensor pressing board 40 and a through hole 71 disposedin a cushion 70 disposed if necessary. The connecting unit 50 may be aribbon cable (not illustrated) connected to a ribbon connector (notillustrated). In this case, preferably, the ribbon cable is attached tothe sensor unit 10 and the ribbon connector is attached to the main bodyunit 20. Use of the ribbon cable can make attachment and detachment ofthe sensor unit 10 and the main body unit 20 easier.

The sensor holder 30 is a board-shaped member which can be bentaccording to the shape of the forehead. A material of the sensor holder30 is not particularly limited, but for example, is a silicone resin ora nylon resin. Preferably, a double-sided adhesive tape is disposed, orsoft elastomer gel-like rubber having reusable self-adhesiveness isdisposed on the forehead-side surface of the sensor holder 30. Bybringing the sensor holder 30 into closer contact with the forehead,entrance of light from the outside into the light receiving units 13,14can be suppressed.

The aperture portion 31 is a through hole disposed in the sensor holder30, and has the light emitting units 11,12 and the light receiving units13,14 disposed therein. The light emitting surfaces of the lightemitting units 11,12 and the light receiving surfaces of the lightreceiving units 13,14 can be exposed toward the forehead. FIG. 1illustrates a form in which the aperture portion 31 has a frame shape,but the present invention is not limited thereto, for example, may be acut-out shape (not illustrated) disposed on an upper end side of thesensor holder 30. A method for holding the sensor unit 10 by the sensorholder 30 is not particularly limited, but for example, is a method forfitting the protrusion 16 a disposed on the probe cover 16 to theaperture portion 31 or a method for fixing the sensor unit 10 to thesensor holder 30 with an adhesive or a pressure-sensitive adhesive.

As illustrated in FIG. 6, a part or the whole of the forehead-sidesurface of the sensor unit 10 is on the same surface as theforehead-side surface of the sensor holder 30. Not illustrated, but apart or the whole of the forehead-side surface of the sensor unit 10 mayprotrude from the forehead-side surface of the sensor holder 30 towardthe forehead-side. Protrusion toward the forehead-side can bring aboutcloser contact with the forehead. For example, when the sensor unit 10has a cross sectional structure illustrated in FIG. 8, a form in which apart of the forehead-side surface of the sensor unit 10 is on the samesurface as the forehead-side surface of the sensor holder 30 orprotrudes is a form in which the light emitting surfaces of the lightemitting units 11,12 and the light receiving surfaces of the lightreceiving units 13,14 are on the same surface as the forehead-sidesurface of the sensor holder 30 or protrude, or a form in which theframe portion 18 surrounding the light emitting units 11,12 and thelight receiving units 13,14 is on the same surface as the forehead-sidesurface of the sensor holder 30 or protrudes. For example, when thesensor unit 10 has a cross sectional structure illustrated in FIG. 9,the form is a form in which the silicone portions 17 a and 17 b are onthe same surface as the forehead-side surface of the sensor holder 30 orprotrude.

The sensor pressing board 40 is a board-shaped member which can be bentaccording to the shape of the forehead. A material of the sensorpressing board 40 is not particularly limited, but for example, is anylon resin or a silicone resin. The sensor pressing board 40 isdisposed between the sensor unit 10 and the main body unit 20, and holdsthe sensor unit 10 toward the sensor holder 30.

The non-invasive monitor for measuring regional saturation of oxygen 1according to the present invention preferably further includes a cushion70 interposed between the main body unit 20 and the sensor pressingboard 40. By bringing the sensor unit 10 into closer contact with theforehead, entrance of light from the outside into the light receivingunit can be suppressed, and measurement can be performed with higheraccuracy. As illustrated in FIG. 2, in the cushion 70, a surface on aside of the main body unit 20 is planar, and a surface on a side of thesensor pressing board 40 has a concave surface shape. A material of thecushion 70 is not particularly limited, but for example, is urethanefoam.

The main body unit 20 includes a housing. A material of the housing isnot particularly limited, but for example, is a hard resin such as anABS resin. The main body unit 20 is disposed in front of the foreheadwhen being mounted on the head. As illustrated in FIG. 3, the main bodyunit 20 preferably has a center mark 22. The position of the center mark22 in a lateral direction of the forehead is on the virtual straightline L (illustrated in FIG. 7). An operator can easily recognize thepositions of the right light receiving unit 13 (illustrated in FIG. 7)and the left light receiving 14 (illustrated in FIG. 7) using the centermark 22 as a guide. By mounting the monitor by matching the center mark22 with the center portion in a lateral direction of the forehead of apatient, the oxygen saturation of the right brain and left brain can bemeasured more securely. The center mark 22 is not particularly limited,but for example, as illustrated in FIG. 3, is obtained by subjecting themain body unit 20 to printing of a substantially rhombic shape anddisposing the vertexes of the substantially rhombic shape on the virtualstraight line L (illustrated in FIG. 7). The center mark 22 may be aprinted dot or line, or may be obtained by embossing on the virtualstraight line L (illustrated in FIG. 7).

The computation processing unit (not illustrated) is, for example, acentral processing unit (CPU). The computation processing unit (notillustrated) is incorporated in the housing. The computation processingunit (not illustrated) calculates a mixed oxygen saturation of the brainblood based on a detection signal detected by the sensor unit 10. Amethod for calculating a mixed oxygen saturation by the computationprocessing unit is, for example, described in Patent Literatures 1 and2. In measurement of a regional saturation of oxygen of a patient bynear-infrared spectroscopy, a deoxyhemoglobin concentration is high in astate indicating a low oxygen saturation level in the brain of thepatient. That is, in a wavelength at which deoxyhemoglobin is absorbedlargely, an optical signal is weak and is easily influenced by anelectrical noise generated by a surrounding electric or electronicdevice. The computation processing unit preferably subjects the weakoptical signal in the state indicating a low oxygen saturation level (astate in which a deoxyhemoglobin concentration is high) toanalog-digital conversion. In this case, in order to improve asignal-noise ratio (S/N ratio), deoxyhemoglobin of a high concentrationcan be measured with high accuracy by disposing an amplifier directly ina photoelectric conversion element to eliminate superimposition ofexternal electrical noise.

The display unit 21 is preferably disposed on a front surface of thehousing. The display unit 21 displays a computation processing result bythe computation processing unit. The computation processing result is,for example, a graph indicating changes over time in an oxygensaturation of the right brain blood, an oxygen saturation of the leftbrain blood, and a mixed oxygen saturation of the brain blood. Thedisplay unit 21 preferably has a structure in which a direction forviewing display contents can be optionally reversed vertically andhorizontally such that a person watching a monitor can confirm thedisplay contents easily at the position without changing the standingposition.

A power source unit (not illustrated) is, for example, a battery such asa disposable primary battery, a secondary battery which can be usedrepeatedly by charging, or a small fuel battery, or an external AC powersource. These may be used singly, or may be used in combination of twoor more kinds thereof. The power source unit is preferably a battery.Incorporation of a battery in the housing can further improveportability. The power source unit (not illustrated) supplies power tothe sensor unit 10, the computation processing unit, and the displayunit 21.

The main body unit 20 preferably has an alarm structure (notillustrated). The alarm structure displays a measurement result on thedisplay unit 21 and emits a primary alarm sound when a regionalsaturation of oxygen (rSO₂) measurement value is, for example, 30% orless, and the alarm structure displays a measurement result on thedisplay unit 21 and emits a secondary alarm sound when the measurementvalue is, for example, 25% or less. A measurement value as a referenceto emit an alarm sound is not limited to 30% or 25%, but the setting canbe changed arbitrarily. Preferably, the alarm sound has a plurality ofsound sources such that the alarm sound can be easily distinguished froman alarm sound emitted by another medical device, and the sound sourcecan be selected and changed arbitrarily.

The main body unit 20 preferably includes a terminal for outputting acomputation processing result to an external apparatus. The main bodyunit 20 preferably has a structure for storing, accumulating, andrecording the computation processing result in an incorporated recordingmedium and recording the computation processing result in a recordingmedium which can be taken outside. The incorporated recording medium is,for example, a flash memory. The recording medium which can be takenoutside is, for example, a SD memory card or a USB memory. Various kindsof data can be input into a monitor apparatus of regional saturation ofoxygen (rSO₂) installed in a hospital to which a patient has beentransported. As a result, continuous data of a regional saturation ofoxygen of a patient in an emergency site can be monitored continuouslyeven after the patient is transported to a hospital, and this canlargely contribute to increase in an emergency life-saving rate of apatient, increase in a cardiopulmonary resuscitation rate, and increasein a social rehabilitation rate of a patient after life-saving.

FIG. 11 is a diagram illustrating a state in which an outer headband islifted. The headband 60 mounts the main body unit 20 on the headdetachably. As illustrated in FIG. 2, preferably, the headband 60includes an inner headband 61 connected to the main body unit 20, anouter headband 62 connected to the outside of the inner headband 61, anda connecting portion 63 connecting the outer headband 62 to the innerheadband 61 so as to be able to be tightened or loosened, the innerheadband 61 includes a slide groove portion 61 a, the connecting portion63 includes a shaft portion 63 b engaging with the slide groove portion,and as illustrated in FIG. 11, the headband 60 can lift the outerheadband 62 around the shaft portion 63 b and can adjust the position ofthe outer headband 62 by sliding the shaft portion 63 b along the slidegroove portion 61 a and matching the headband with the size of the head.The monitor can be mounted on a patient more easily.

The inner headband 61 is mounted on a side of the head of a patient. Amaterial of the inner headband 61 is not particularly limited, but forexample, is a nylon resin or a silicone resin. The inner headband 61includes the slide groove portion 61 a. The slide groove portion 61 a isdisposed in a length direction of the inner headband 61. The slidegroove portion 61 a is preferably a through hole penetrating in athickness direction of the inner headband 61. A cushion 64 is preferablydisposed on a patient-side surface of the inner headband 61. A materialof the cushion 64 is not particularly limited, but for example, isurethane foam.

The outer headband 62 is mounted over a side of the head of a patient tothe back of the head. A material of the outer headband 62 is notparticularly limited, but for example, is a nylon resin or a siliconeresin. A cushion 65 is preferably disposed on a patient-side surface ofthe outer headband 62. A material of the cushion 65 is not particularlylimited, but for example, is urethane foam.

As illustrated in FIG. 2, the connecting portion 63 preferably includesa helical head portion 63 a and the shaft portion 63 b. The connectingportion 63 has a tightening and loosening structure. For example, thetightening and loosening structure provides a nut (not illustrated)engaging with the slide groove 61 a slidably in the slide groove 61 a,and screws a lower end of the shaft portion 63 b into the nut. The outerheadband 62 can be lifted around the shaft portion 63 b by turning thehelical head portion 63 a in a loosening direction, the shaft portion 63b can slide along the slide groove 61 a, and the outer headband 62 isfixed to the inner headband 61 by turning the helical head portion 63 ain a tightening direction in a state in which the outer headband 62 isdisposed at a predetermined position.

FIG. 12 is a diagram illustrating a state in which the monitor ismounted on a person having a small head. FIG. 13 is a diagramillustrating a state in which the monitor is mounted on a person havinga large head. Next, a method for mounting the non-invasive monitor formeasuring regional saturation of oxygen 1 on a patient will be describedwith reference to FIGS. 11 to 13. First, as illustrated in FIG. 11, anoperator mounts a sensor unit surely on the cranium (frontal lobe) of apatient in a state in which the outer headband 62 is lifted upward, andthen restores the outer headband 62 to a horizontal state. Subsequently,as illustrated in FIGS. 12 and 13, the operator adjusts the position ofthe outer headband 62 by sliding the shaft portion 63 b along the slidegroove portion 61 a and matching the headband with the size of the head.Finally, the operator fixes the outer headband 62 to the inner headband61 by turning the helical head portion 63 a in a tightening direction tomount the non-invasive monitor for measuring regional saturation ofoxygen 1 on a patient. Thereafter, the operator starts measurement of aregional concentration of oxygen.

FIG. 14 is a diagram illustrating a state in which a tightening tool istightened. FIG. 15 is a diagram illustrating a state in which atightening tool is loosened. The non-invasive monitor for measuringregional saturation of oxygen 1 according to the present inventionpreferably further includes a tightening tool 80 connected to the sensorpressing board 40. By bringing the sensor unit into closer contact withthe forehead by tightening the sensor pressing board 40 with thetightening tool 80 after mounting the non-invasive monitor for measuringregional saturation of oxygen 1 on a patient, entrance of light from theoutside into the light receiving unit can be suppressed, and measurementcan be performed with higher accuracy. The tightening tool 80 is onlyrequired to have a structure which can be tightened and loosened, andthe structure is not particularly limited. An example of the structureof the tightening tool 80 is a structure in which a belt portion 81 anda lock portion 82 are included as illustrated in FIG. 14, the beltportion 81 is fixed to a predetermined position by engagement betweenthe belt portion 81 and the lock portion 82, and tightening by the beltportion 81 can be loosened by releasing the lock portion 82 asillustrated in FIG. 15. The belt portion 81 preferably protrudes out ofthe headband 60. A tightening work can be performed more easily. Forexample, a form in which the belt portion 81 protrudes out of theheadband 60 is a form in which the belt portion 81 is connected to bothends of the sensor pressing board 40 in a lateral direction of theforehead and the belt portion 81 protrudes out of the headband 60 from athrough hole 62 a disposed in the outer headband 62 through the slidegroove portion 61 a of the inner headband 61.

Next, an action of the non-invasive monitor for measuring regionalsaturation of oxygen 1 will be described. First, the light emittingunits 11,12 sequentially output laser light having a predeterminedwavelength (for example, 730 nm or 810 nm) based on a signal indicatedby CPU (not illustrated). The laser light is emitted from a lightemitting surface toward the forehead, and enters the head. The laserlight which has entered the head propagates while being scattered in thehead and absorbed by a component to be measured, and a part of the lightreaches an optical detection position. The laser light which has reachedthe optical detection position is detected by the light receiving units13,14. Each of the light receiving units 13,14 generate a photocurrentcorresponding to the intensity of the detected laser light. Thesephotocurrents are converted into a voltage signal (detection signal) bya preamplifier (not illustrated), and these voltage signals areconverted into digital signals by an A/D conversion circuit.

Subsequently, the computation processing unit (for example, CPU)calculates a hemoglobin oxygen saturation (TOI) based on digital signalsD(1) to D(N). CPU calculates a temporal relative change amount of anoxygenated hemoglobin concentration (ΔO₂Hb) using at least one digitalsignal among the digital signals D(1) to D(N), and calculates one orboth of a temporal relative change amount of a deoxygenated hemoglobinconcentration (ΔHHb) and a temporal relative change amount of the totalhemoglobin concentration which is the sum of these amounts (ΔcHb), ifnecessary. CPU removes a frequency component smaller than apredetermined frequency f₀ among frequency components contained in theserelative change amounts (ΔcHb, ΔO₂Hb, ΔHHb) by filtering. These relativechange amounts after filtering (ΔcHb, ΔO₂Hb, ΔHHb) and time-series dataindicating these amounts are displayed on the display unit 21.

FIGS. 1 to 15 illustrate a form in which a pair of the light emittingunits 11,12 and the light receiving units 13,14 is disposed in linearsymmetry with respect to a lateral direction of the forehead, but thepresent invention is not limited thereto, but for example, may be a formin which the light emitting unit 11 and the light receiving unit 13 arepresent only on the right with respect to the lateral direction of theforehead or a form in which the light emitting unit 12 and the lightreceiving unit 14 are present only on the left with respect to thelateral direction of the forehead. A form in which the number of thelight receiving unit 13 or the light receiving unit 14 is three has beendescribed, but the present invention is not limited by the number of thelight receiving units 13,14, and for example, the number of the lightreceiving unit 13 or the light receiving unit 14 may be one, two, orfour or more.

FIG. 16 is a schematic diagram illustrating a modification example of amain body unit. As illustrated in FIG. 16, the main body unit 20preferably has a button 23. The button 23 is, for example, a powerbutton 23 a or a reset button 23 b. The button 23 is a press button oran icon displayed on a touch panel. FIG. 3 illustrates a form in whichthe main body unit 20 includes one display unit 21, but the presentinvention is not limited thereto. For example, as illustrated in FIG.16, a first display unit 21 a for displaying right brain informationincluding a graph indicating changes over time in an oxygen saturationof the right brain blood and a mixed oxygen saturation of the rightbrain blood, and a second display unit 21 b for displaying left braininformation including a graph indicating changes overtime in an oxygensaturation of the left brain blood and a mixed oxygen saturation of theleft brain blood may be disposed. In this way, by displaying the rightbrain information and the left brain information separately, an operatorcan determine the right brain information and the left brain informationmore surely and instantaneously. The display unit 21 (21 a and 21 b) maydisplay a remaining battery capacity or time in addition to a mixedoxygen saturation of the brain blood.

REFERENCE SIGNS LIST

-   1 non-invasive monitor for measuring regional saturation of oxygen-   10 sensor unit-   11 light emitting unit (right light emitting unit)-   12 light emitting unit (left light emitting unit)-   13 light receiving unit (right light receiving unit)-   14 light receiving unit (left light receiving unit)-   13 a,14 a light receiving unit for a shallow portion-   13 b,14 b light receiving unit for a deep portion-   15 printed circuit board-   16 probe cover-   16 a protrusion-   17 covering portion-   17 a,17 b silicone portion-   17 c light transmission hindering portion-   18 frame portion-   21 display unit-   20 main body unit-   21 display unit-   21 a first display unit-   21 b second display unit-   22 center mark-   23 button-   23 a power button-   23 b reset button-   30 sensor holder-   31 aperture portion-   40 sensor pressing board-   41 through hole-   50 connecting unit-   60 headband-   60 headband-   61 inner headband-   61 a slide groove portion-   62 outer headband-   63 connecting portion-   63 a helical head portion-   63 b shaft portion-   64 cushion-   65 cushion-   70 cushion-   71 through hole-   80 tightening tool-   81 belt portion-   82 lock portion-   91 light transmission hindering portion-   91 a aperture-   92 silicone portion

The invention claimed is:
 1. A non-invasive monitor for measuringregional saturation of oxygen for measuring an oxygen saturation of abrain blood stream continuously in a non-invasive manner by mounting themonitor on a person's head, comprising: a sensor unit including aprinted circuit board on which a light emitting unit for irradiating asurface of the forehead of the head with light of 650 to 1000 nm and alight receiving unit for receiving light which has been emitted by thelight emitting unit and has propagated inside the head are mounted,wherein the sensor unit is a board-shaped member that is bent accordingto the shape of the forehead; a main body unit disposed in front of theforehead when being mounted on the head, including a computationprocessing unit for calculating a mixed oxygen saturation of the brainblood based on a detection signal detected by the sensor unit, a displayunit for displaying a computation processing result by the computationprocessing unit, and a power source unit for supplying power to thesensor unit, the computation processing unit, and the display unit; asensor holder for holding the sensor unit while the light emitting unitand the light receiving unit are disposed in an aperture portion, havinga board shape abutting on the forehead and including the apertureportion penetrating in a board thickness direction thereof, wherein thesensor holder is a board-shaped member that is bent according to theshape of the forehead; a sensor pressing board for holding the sensorunit toward the sensor holder, disposed between the sensor unit and themain body unit, wherein the sensor pressing board is a board-shapedmember that is bent according to the shape of the forehead; a connectingunit for electrically connecting the sensor unit and the main body unit;and a headband for mounting the main body unit on the head detachably,wherein the sensor holder, the sensor unit, the sensor pressing board,and the main body unit are integrated by being stacked in this orderfrom the forehead-side, wherein the light emitting unit and the lightreceiving unit are disposed such that a light emitting surface of thelight emitting unit and a light receiving surface of the light receivingunit face the forehead-side, and a part or the whole of theforehead-side surface of the sensor unit is on the same surface as theforehead-side surface of the sensor holder or protrudes from theforehead-side surface of the sensor holder toward the forehead-side,wherein the sensor unit includes a right light emitting unit and a leftlight emitting unit as the light emitting unit and includes a rightlight receiving unit and a left light receiving unit as the lightreceiving unit, and the left light receiving unit, the left lightemitting unit, the right light emitting unit, and the right lightreceiving unit are disposed in this order in a lateral direction of theforehead, wherein the left light emitting unit and the right lightemitting unit are disposed in linear symmetry with a virtual straightline between the left light emitting unit and the right light emittingunit as a symmetric axis, wherein the left light receiving unit and theright light emitting unit are disposed in linear symmetry with thevirtual straight line as a symmetric axis, wherein the right lightemitting unit and the right light receiving unit is for measuring theoxygen saturation of the right brain, and the left light emitting unitand the left light receiving unit is for measuring the oxygen saturationof the left brain, and wherein the main body unit has a center mark, andthe position of the center mark in a lateral direction of the foreheadis on the virtual straight line.
 2. The non-invasive monitor formeasuring regional saturation of oxygen according to claim 1, furthercomprising a cushion interposed between the main body unit and thesensor pressing board.
 3. The non-invasive monitor for measuringregional saturation of oxygen according to claim 1, wherein the headbandincludes an inner headband connected to the main body unit, an outerheadband connected to the outside of the inner headband, and aconnecting portion connecting the outer headband to the inner headbandso as to be able to be tightened or loosened, the inner headbandincludes a slide groove portion, the connecting portion includes a shaftportion engaging with the slide groove portion, and the headband canlift the outer headband around the shaft portion and can adjust theposition of the outer headband by sliding the shaft portion along theslide groove portion and matching the headband with the size of thehead.
 4. The non-invasive monitor for measuring regional saturation ofoxygen according to claim 1, further comprising a tightening toolconnected to the sensor pressing board.
 5. The non-invasive monitor formeasuring regional saturation of oxygen according to claim 1, whereinthe connecting unit is a connector.
 6. The non-invasive monitor formeasuring regional saturation of oxygen according to claim 1, whereinthe sensor unit includes a covering portion for covering a part or thewhole of the forehead-side surface of the sensor unit, and the coveringportion is configured to transmit the light at least in a siliconeportion covering the light emitting surface-side of the light emittingunit and the silicone portion covering the light receiving surface-sideof the light receiving unit.
 7. The non-invasive monitor for measuringregional saturation of oxygen according to claim 6, wherein the coveringportion includes a light transmission hindering portion at least betweenthe silicone portion covering the light emitting unit and the siliconeportion covering the light receiving unit, and in comparison with unitthickness, a material of the light transmission hindering portion isable to transmit light at a maximum of ten percent of a material of thesilicone portion.
 8. The non-invasive monitor for measuring regionalsaturation of oxygen according to claim 1, wherein the sensor unitincludes a light receiving unit which receives light that has passedthrough a shallow layer of the brain and a light receiving unit whichreceives light that has passed through a deep layer of the brain as thelight receiving unit.
 9. The non-invasive monitor for measuring regionalsaturation of oxygen according to claim 2, wherein the cushion has aplanar surface on a side of the main body unit and a concave-shapedsurface on a side of the sensor pressing board.
 10. The non-invasivemonitor for measuring regional saturation of oxygen according to claim4, wherein the tightening tool includes a belt portion connected to thesensor pressing board and a lock portion which fixes the belt portionand has a structure in which the belt portion is fixed to apredetermined position by engagement between the belt portion and thelock portion and tightening by the belt portion can be loosened byreleasing the lock portion.
 11. The non-invasive monitor for measuringregional saturation of oxygen according to claim 5, wherein theconnector is connected to a recess type connector disposed in the mainbody unit through a through hole disposed in the sensor pressing board,and the connector also serves as a fixing tool for fixing the sensorunit to the main body unit.